When it all comes right down to it: what, and who makes up your true "covenant community"? If many professing Christians were honest with themselves, they would have to admit, to their utter shame (if they understood the gravity of the situation), that something other than the church was their principal source of encouragement, passion, and concern.
The reason this arrangement is reprehensible, is because it flies in the face of God, and of His generous and gracious provision, of His Son, and of His church. It raises a puny fist of idolatry up, against God.
I have known people who were much more solicitous of others who shared their approach to their children's educational context, than they were of the people of God, with whom they were allegedly "bound," by covenant (in the church). They would be more inclined to allow their children access to like-minded educators, than they would the people in the church (who did not share their methodology).
For these people church is more of a convenience, than a necessity. And, instead of serving her (the church), they view it as a prosyletizing field, out of which they hope to make converts to their truest and dearest interests.
No wonder Jude spoke of these people as those who "Crept in unnoticed, who long ago were marked out for . . . condemnation," (Jude 4).